1. FIELD OF THE INVENTION
The invention relates to a ceramic gas burner for a combustion chamber of a hot-blast stove, e.g. a hot-blast stove of a blast furnace.
2. DESCRIPTION OF THE PRIOR ART
A burner of this type is described in EP-A-90096 which has parallel vertical supply ducts for the two combustion components (gas and air). A first one of these ducts opens upwardly at a first outlet opening which in plan view is essentially rectangular in shape, while the second duct opens at second outlet openings which are on each side of and above the first outlet opening. The outflow directions of the second outlet openings are oblique to that of the first outlet opening.
In the long sides of its first outlet opening this burner has a plurality of recesses extending outwardly towards the second outlet openings. These recesses are provided for alternate second outlet openings on each long side of the first outlet opening. The recesses on the two long sides of the first outlet openings are staggered, so that no recess on one long side is opposite a recess on the other long side.
In burners for hot-blast stoves it is important that no combustible components from the combustion gas remain unburnt, or that scarcely any such combustible components remain unburnt. On the other hand it is desirable to reduce the excess of air required for combustion in order to achieve as high as possible a flame temperature at a specific calorific value of the combustion gas. It is known that improving the mixing of gas and air helps to achieve these objectives.
The object of the invention is to improve the mixing of the gaseous components in the burner of EP-A-0090096. Other advantages may be achieved, which will be explained in the following.
The ceramic burner in accordance with the invention is characterised in that, with respect to each recess in a first one of the long sides of the first outlet opening, there is correspondingly one recess directly opposite in the second long side of the first outlet opening.
It is preferable that for each of the second outlet openings of the burner, there is correspondingly one of the recesses.
This particularly simply shaped burner achieves a very intensive mixture at many places along the long sides of the first outlet opening, which, by lowering the point where the turbulence generated is complete, leads to a more stable flame and lower quantities of unburnt combustible component remaining.
A particular advantage is obtained with the burner in accordance with the invention, if it is constructed from a pack of shaped bricks. Through the greater regularity of the shape of the burner in accordance with the invention, it has been found possible to achieve considerable savings, e.g. of up to 80%, in the number of different shaped bricks used.
It is advantageous if the recesses, as seen in the outflow direction, have outwardly widening cross sections. Preferably this widening is in the direction perpendicular to the long sides of the first outlet opening.